Traveling wave tube devices

In a traveling wave tube of the type provided with an electron gun, a high frequency circuit unit connected thereto and comprising a cavity resonator type delay circuit unit, a collector unit disposed on the output side of the said high frequency circuit unit and adapted to receive an electron beam sent via said high frequency circuit unit, a beam focusing unit disposed adjacent to said high frequency circuit unit and adapted to cause a periodic magnetic field to act upon the electron beam passing through the high frequency circuit unit, and input/output units connected to the electron gun side of said high frequency circuit unit and the end portion of the collector unit side, a waveguide portion connected to the output unit of said high frequency circuit unit comprises a column-shaped waveguide member having an end surface forming a portion of the wall of a cavity at the end of the high frequency circuit unit, said member being bored with a central aperture at a central axis to allow the passage of the electron beam from the electron gun to the collector unit, said central aperture is tapered and its diameter increases towards the collector unit, and a waveguide for transmitting the electromagnetic waves from said end surface to the output unit, said end surface of the waveguide being shaped like a fan.